Together with husband Michael Wynn-Jones, she has bought the 42 per cent shareholding of the 84-year-old club president, Geoffrey Watling, for an undisclosed sum.
Smith, who joined the Carrow Road board with her husband last year, said she was delighted to be increasing her involvement with the Canaries.
"It's extremely exciting and gives us an awful lot of pleasure," she said. "I think everyone wants to give the talents they have."
Though Smith is thought to have amassed a private fortune of around pounds 17m, she professes to have no business expertise.
"If you showed me a profit and balance sheet I wouldn't know which way to hold it up," she said, "but I have other gifts. It's nice when you reach middle age and can go in another direction."
Barry Lockwood will remain as chairman but Wynn-Jones said he and his wife intended to make use of their increased power.
"Obviously it does throw a lot more responsibility our way," he said. "It's a way of getting more involved with the club. What we have realised in a year are the problems and the challenges.
"The more you get to know about the club and football in general the more and more daunting it gets. We do look at this as a chance to have an authoritative voice."
Besides her football-related activities, Smith, who lives in Stowmarket, Suffolk, runs two large companies and works as an advisor to Sainsbury's and British Airways. It was these commitments, as well as an imminent 20-part cookery series on television, that led her to turn down Mr Blair's offer of a peerage following Labour's victory in the General Election.
Since she became involved in Norwich City, there have been a few changes, such as a Bruce Oldfield-designed strip. Whether the players can look forward to a new nutritional regime is another matter. DELIA'S RECIPE FOR SUCCESS? Gazzapacho Something to dribble down your shirt Spanish omelette Load of fancy foreigners to enliven a dull team on the cheap Spicy chicken wing-backs Time for Norwich to embrace the tactical flavour of the month Toad in the hole Playing just behind the two strikers Beef Wellington (with sponsor's mustard on the side) Put some weight into big boots out of defence Carrow Cake Helps players see the goal in evening matches Nottingham Forest Gateau An alluring target at the end of the meal Chase and biscuits No takers, yesterday's chef, bit rich anyway